Thursday, March 31, 2016

Exterior Lights

A couple of people have suggested that I do a post on exterior lights. As it happens, I've done bits and pieces on the subject so herewith a summary of what I know so far. At the moment, it's a work in progress. Comments, additions, and corrections are welcome.

Note that the colors refer to the tint of the clear plastic cover over the light bub, not the bulb itself.

An overview of lights on the wing in the 1950s:

Position/Navigation/Running Lights

These are the standard red (left wingtip), green (right wingtip), white (tail) lights. On some late 1940s and 1950s Navy airplanes, there is a separate orange tail light. This appears to be a holdover from a pre-World War II CAA (the forerunner of the FAA) requirement for separate orange and white tail lights that would flash alternately (white-orange-white- orange) to improve visibility at night. Those on the AD Skyraider were on both sides of the fin and viewable from the rear.

Anti-collision Lights

As a result of the midair collision of two civil airliners over the Grand Canyon in 1956, the CAA required anti-collision lights (rotating or flashing beacons) on aircraft for which type certificate applications were submitted after 1 April 1957. (Presumably, there was also a retrofit requirement.) My understanding is that the armed services were not obligated to comply, but they had midair collision concerns of their own so they were added. (When the Israelis got used A-4 Skyhawks, they were amused that they came with a red police-car gumball light.) Note that the anti-collision lights on the A3J Vigilante were retractable.

On aircraft with a long service life like the AD Skyraider, anti-collision lights were a retrofit. Blue-painted ones generally didn't have the anti-collision light on the top of the vertical fin while gray/white ones did.

On some air-refueling tankers the anti-collision light on the bottom of the fuselage was green instead of red to differentiate them at night from other airplanes in the vicinity.

These were added at some point in the early 1940s for IFF (Identification Friend or Foe) and signaling purposes. They consisted of three lights, red/green/amber, on the fuselage belly or under the right wing and a white light on the top of the fuselage (I'm not sure how standard the white light was).

The lights could be separately turned on and off and also used to flash a Morse code signal with a "key" switch.

Landing and Taxi Lights

Some aircraft were fitted with landing and/or taxi lights. The first F4U Corsairs had a retractable light under the left wing but it disappeared early on in production. (It was not, as some would have you believe, replaced by a light in the wing leading edge. That was the approach light and it had been there since the XF4U-1)

Formation Lights

At some point in the 1940s, formation lights were instituted for use at night. At least at first, these were blue lights "embedded" in the upper surface of the outboard wing panels along with one on the top of the fuselage, often described as a "section light". These are notable on the Vought F4U and Grumman F6F, TBF, and F8F. For the latter, see http://tailhooktopics.blogspot.com/2013/02/f8f-formation-lights.html

Much later on, formation lights were small rectangles on the side of the fuselage along with a light on each wingtip separate from the position lights. These were eventually replaced by larger and more numerous so-called "slime" lights that appeared to be yellow when not lit in daylight and a glow-stick green when lit at night.

1 comment:

Nice summation of external lighting. Adding to what you have written, some US aircraft, such as the B-24 and B-25, in the early 1940's, had a red spotlight in the leading edge of the left wing. This light was referred to as a "passing light". The light was to be turned on or left on when in the vicinity of other aircraft to provide notice of aircraft proximity. Before the appearance of the red/green/amber recognition lights, a white recognition light was installed on the upper and lower surface of the fuselage. These two lights could be controlled separately or in combination with selective or keying switches. Again, this installation was found on early versions of aircraft such as the B-24 and B-25.

About Me

In 1956, at age 12, I lived on NAS Sangley Point in the Philippine Islands. Always enamored with airplanes, I imprinted on the Cougars, Banshees, and Skyraiders then being deployed. Not able to be a Naval Aviator because I was nearsighted, I instead became an aeronautical engineer and general aviation pilot. Now retired, I write books and monographs on U.S. Navy aircraft.